Technical Field
The present disclosure relates to methods and/or apparatuses for a node to determine time to live of a path.
Description of the Related Art
The term “time to live” refers to a time period or a mechanism that limits the lifespan or lifetime of data in a computer or network. In a design of a routing algorithm, time to live of a path is a key factor affecting a performance of the algorithm. If the time to live of the path is set to be too short, a frequent routing expiration may occur, thereby undesirably increasing routing maintenance cost and/or time delay of data transmission. If the time to live of the path is set to be too long, a data packet is still transmitted with an expired routing, thereby causing a higher packet loss rate and/or a longer time delay. Therefore, accurate time to live of the path can improve the performance of the routing algorithm.
In existing routing algorithms, methods for determining time to live of a path are mainly as follows:
I. Providing each path with the same time to live.
II. Determining time to live of a path by determining time to live values of respective links by predicting when a link between neighboring nodes will be disconnected based on geographical position information and movement speed information of respective nodes.
III. Setting time to live of a path based on energy states of a respective nodes in the path.
However, the existing methods for determining the time to live of the path as mentioned above have the following issues.
In the first method, properties of different links are not considered.
In the second method, the geographical position information and the movement speed information of the node should be obtained through a GPS or another method, and the obtained information should be added into a routing control packet. This method may be useful in a high-speed movement scenario. However, this method needs assistance of an additional mechanism (e.g., a GPS), and thus increases a cost of the routing control packet.
The third method is only applicable in a network (e.g., a wireless sensor network (WSN)) powered by a battery. this method is not applicable to a scenario where each node is supplied by a power source.